The present invention relates to sorbent materials. More particularly the present invention relates to sorbent wipers suitable for various industrial uses.
Improvements in the manufacturing of high technology items such as micro-electronic devices or integrated circuits have necessitated the maintenance of essentially a xe2x80x9cclean roomxe2x80x9d atmosphere. Integrated circuits typically include a desired pattern of components which generally include a series of electrically active regions and electrical insulation regions located within a semi-conductor wafer. The electrically active regions within the semiconductor body or wafer are then interconnected with a detailed metallic electrical interconnection pattern in order to obtain the desired operating characteristics. The formation of the electrically active or insulation regions and the corresponding electrical interconnects involve a significant number of different processes well known in the art, examples being chemical vapor deposition of conductors and insulators, oxidation processes, solid state diffusion, ion implantation, vacuum depositions, various lithographic techniques, numerous forms of etching, chemical-mechanical polishing and so forth. A typical integrated circuit fabrication process utilizes a great number of cycles, each of which may utilize a specific sequence of one or more of the above processes.
Many of the components of an integrated circuit made by the aforesaid processes are of such a minute size and/or thickness that the presence of even minor levels of contaminants can be fatal to fabrication of the integrated circuit. For example, by normal standards small bits of lint or dust are not problematic but due to the relative size of the components of an integrated circuit such contaminants can bridge interconnects or insulation regions and cause defects within the device. Therefore, there is a need to maintain all surfaces and workpieces free from such contamination. This is usually accomplished in part by wiping these surfaces, and a number of specialized wipers have been developed for this purpose. However, it is critical that the wiper efficiently cleans surfaces and does not itself release dust, lint or other particulate matter. Various nonwoven wipes are available, but while some are low linting, these require treatment for wettability in order to provide the absorbency and clean wiping characteristics desired for clean room applications. Such treatments typically utilize anionic wetting agents that are high in sodium ion content. These metallic ions present special problems since, if present in high concentrations, they may change the electrical properties of sensitive electrical components and/or cause defects therein.
In addition, sorbent materials having the ability to dissipate charges are less likely to develop or release a static charge. In this regard, sorbent materials used in proximity to electrically sensitive devices, such as integrated circuits and/or micro-electronic devices, desirably have good anti-static properties. Although the current generated from static electricity is small by many standards, it is relatively large with respect to the electrical load intended to be carried by interconnection patterns within integrated circuits and other micro-electronic devices. Thus, static electricity can be fatally destructive to such devices. In addition, when collecting or containing flammable liquids it is likewise highly desirable that the wipers have excellent anti-static properties in order to avoid igniting the same. However, although anti-static properties are often desirable, use of conventional ionic compounds that impart anti-static properties can negatively impact the emulsion stability or absorbency characteristics of the sorbent materials.
In addition, sorbent materials desirably exhibit the ability to quickly absorb or wick liquid into the article. Sorbent materials, particularly wipes, which do not quickly absorb liquids, make it more difficult to remove or collect liquids from a hard surface. Further, sorbent materials desirably exhibit the ability to retain such liquids once wicked into the fabric. When sorbent materials cannot retain absorbed liquid they tend to leak or drip fluid once removed form the supporting surface. This can be disadvantageous in making clean up more difficult and/or by further spreading undesirable liquids. Thus, sorbent materials that can quickly absorb significant capacities of liquids and which also have the ability to retain the same are highly desirable. Further, sorbent materials capable of absorbing a wide variety of liquids are likewise highly desirable.
Accordingly, there exists a need for sorbent materials which are suitable for use with clean room applications and which have low metallic ion concentrations. Further, there exists a need for such sorbent materials that have excellent anti-static properties. Still further, there exists a need for sorbent materials a web that have excellent antistatic properties and that also exhibit excellent absorbency characteristics.
The aforesaid needs are fulfilled and the problems experienced by those skilled in the art overcome by the sorbent materials of the present invention. In one aspect of the invention, the sorbent material can comprise a porous substrate having a wetting chemistry upon the surfaces thereof comprising: (a) an aliphatic alcohol ethoxylate; and (b) a surfactant selected from the group consisting of an alkyl sulfosuccinate, an alkyl sulfate and/or a sulfated fatty acid ester. Desirably, the parts by weight ratio of the components, a:b, ranges from about 9:1 to about 1:1, respectively.
In a further aspect, the present invention also provides a sorbent material having excellent anti-static properties comprising a porous substrate having a wetting chemistry upon the surfaces thereof comprising: (a) an alcohol ethoxylate selected from the group consisting of an alkyl alcohol ethoxylate, an aryl alcohol ethoxylate and halogenated analogs thereof; (b) a surfactant selected from the group consisting of an alkyl sulfosuccinate, an alkyl sulfate and a sulfated fatty acid ester; and (c) a fatty acid ester ethoxylate such as, for example, a poly(ethylene glycol)ester. Desirably the components of the wetting chemistry, a:b:c, are in a weight ratio of approximately 1:1:1 to about 4:1:1, respectively. The wetting chemistry can be applied to a porous substrate such as a nonwoven web. As a particular example, the wetting chemistry can be applied to a nonwoven web of polyolefin meltblown fibers such that the wetting chemistry comprises from about 0.1% to about 5% of the treated web.